Robot Boundary Control With Haptic Return Guidance

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Solution Overview

Problem

Existing robot control methods are difficult and non-intuitive, especially when dealing with complex boundaries defined by curved hypersurfaces, as they require manual testing to trigger safety actions, which can be challenging and unsafe.

Innovation Solution

A method that allows robots to operate in two modes: the first mode triggers safety reactions when limits are exceeded, while the second mode applies a motor-driven actuating force to return the robot to a safe position, providing haptic feedback and allowing safe testing of limits without triggering safety reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual testing is used to trigger safety actions by guiding the robot to limits, then safety monitoring can be tested, but the process becomes difficult and non-intuitive especially with complex curved hypersurface boundaries

Engineering Contradiction:
Improvesafety monitoringVSAvoidtesting process
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces manual mechanical guidance testing with an automated computational method. The control device automatically determines distances to boundaries in the state space and triggers safety actions based on these calculations, eliminating the need for manual robot guidance to limit positions and making the testing process intuitive and systematic.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs self-testing by automatically calculating distances from the robot's current state to predefined boundaries and determining whether safety actions should be triggered. This self-service approach eliminates the need for external manual testing while ensuring reliable safety monitoring of complex curved hypersurface boundaries.

Inventive Principle:
Principle #25Self-service

2Reliability

If the robot is stopped with interrupted power supply when limits are exceeded, then safety is ensured, but the robot cannot be used for training purposes where exceeding limits is intentional

Engineering Contradiction:
ImprovesafetyVSAvoidoperating modes
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic switching between two operating modes: a first mode for normal operation where safety actions are triggered when limits are exceeded, and a second training mode where the robot can intentionally exceed limits without triggering safety stop. This dynamic adaptability allows the same robot system to serve both safety-critical operations and training purposes.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameters by switching between different operating modes. In the first operating mode, the distance threshold for triggering safety actions is effectively zero. In the second operating mode, the system allows intentional exceeding of limits by changing the operational context, enabling training while maintaining the ability to enforce safety when needed.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If haptic feedback is provided through motor-driven actuating force to guide the robot back to safe position, then intuitive control is achieved, but additional actuating mechanisms are required

Engineering Contradiction:
Improvecontrol intuitivenessVSAvoidactuating mechanisms
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent makes the existing robot actuators serve multiple functions: they perform both the primary task of moving the robot and the secondary function of providing haptic feedback by applying corrective forces when boundaries are approached. This multi-functionality eliminates the need for separate haptic feedback mechanisms while achieving intuitive control.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system merges the motion control function with the haptic feedback function into a single integrated control mechanism. The motor-driven actuating force that guides the robot back to safe position is combined with the boundary monitoring system, creating a unified control approach that provides intuitive haptic feedback without requiring additional dedicated haptic devices.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP2977148B1Method and device for controlling a robot
Publication Date: 2023.11.29 KUKA DEUT GMBH
  • EP2977148B1 patent drawingFigure 1~3
  • EP2977148B1 patent drawingFigure 2
  • EP2977148B1 patent drawing

AI summary

According to a method according to the invention, a distance (d) of a state variable (x2) of the robot from a first Boundary (G1, G2) determined (S40); and a safety reaction (STOP 1) triggered (S60) if the distance satisfies a first condition (d > 0); and in the second operating mode in which the robot can be moved by manually applying a guiding force to the robot; the distance of the state variable of the robot from the first boundary is determined (S70); the safety response is not triggered because the distance satisfies the first condition; and a positioning force (F) is applied by motor to the robot as a function of the distance (S110) in order to reduce the distance when the robot is unhindered if the distance satisfies the first condition. Additionally or alternatively, to move the robot by manually applying a guiding force to the robot in an operating mode (M2), a distance (d) of a state variable (x1) of the robot from at least two different predetermined references (yn, yn+1, B) determined in a state space ({xi, xj}) of the robot (S200); the smallest (dmin) of the distances determined (S210-S270); and a positioning force (f) is applied by motor to the robot (S280) in order to minimize the smallest of the distances when the robot is unhindered.